1. Field of the Invention
This invention relates generally to a system and method for providing a vehicle roll stability indicator that is indicative of the potential for vehicle rollover and, more particularly, to a system and method for providing a vehicle roll stability indicator that is indicative of the potential for vehicle rollover, where determining the roll stability indicator includes calculating vehicle roll energy, roll energy rate, tire lateral load transfer and wheel airborne duration.
2. Discussion of the Related Art
It is known in the art to provide vehicle control enhancement using differential braking control, rear-wheel steering control, front-wheel steering control, or any combination thereof to help prevent a vehicle from encountering conditions that present an increased possibility of rollover. These systems may receive vehicle dynamics information from various sensors, such as yaw rate sensors, lateral acceleration sensors and tire/wheel sensors to determine the proper control action. These systems may also incorporate roll-rate sensors and roll angle estimation features in order to estimate rollover possibility during a maneuver and provide responsive control enhancement. A balance typically needs to be provided between controlling the vehicle roll motion and the vehicle yaw motion to provide the optimal vehicle response. Thus, it is usually necessary to detect certain vehicle conditions to provide the optimized vehicle control enhancement.
Various methodologies are known in the art to detect these vehicle conditions. Rollover determination can be based on vehicle roll rate from a roll rate sensor and roll angle estimation. Even though roll rate and roll angle are the two most important elements for detecting vehicle roll motion, they do not reflect the total vehicle roll energy that would eventually determine the probability of rollover.